Which Mattress is better for Back pain people?

Hi All,

I recently joined in a warehouse firm although it's a tough job, it is offering me a good amount of money, so I thought of joining. As work piled up the pressure to meet up the targets was enormous for me. The only thing I wanted was a good night sleep after a long day of work. Recently, I started to have some severe back pain when I wake up. At first I thought it's because of the work as I have to lift things It's normal to have pain as you enter a new type of job. But the pain continued for the coming week as well. So I visited the nearby clinic and had a detailed check up so the doctor told me, "your work can be a reason for the moment" and he told me to take some pills and try not to lift heavy stuff and I did as per his instruction but it didn't seem to work out well. I did go again for a checkup and I told him I did do as you said but still it's not working. So he asked me, "have you checked your mattress? Is there any stiffness or uneven surface which can be the reason as well". I came home and checked it, I did find some uneven surface I called the doctor and told him about the mattress he told "you should immediately need to replace the mattress". So I checked into some mattress stores but I need to know which one can be the right one for me I am 5'11 ft and 165lbs I am a side sleeper which mattress can be a good choice for me please advice?